One of the types of cluster sampling technique in which areas (for example, census tracts, blocks) serve as the primary sampling units. The population is divided into mutually exclusive and exhaustive areas using maps, and a random sample of areas is selected. If all the households in the selected areas are used in the study, it is one-stage area sampling, while if the areas themselves are sub-sampled with respect to households; the procedure is called two-stage area sampling.